1. Field of the Invention
The present invention relates to an optical component, an optical sensor, a surface plasmon sensor and more particularly, to a surface plasmon sensor for measurement and for fingerprint matching, and an optical component and an optical sensor, etc., used in the above surface plasmon sensor.
2. Description of the Related Art
A surface plasmon sensor using a surface plasmon resonance (SPR) is a sensor that can measure a small amount of antigen, etc with high accuracy in a nondestructive manner. As human DNA sequencing has advanced, a study for using its development has been advancing. Thus, there is a need for a biosensor that can detect protein, DNA, the reaction between an antigen and an antibody at high speed and sensitivity, and thus the surface plasmon sensor has also been used as a biosensor.
FIG. 1 shows a sectional view of the structure of a surface plasmon sensor disclosed in Japanese Patent Application Laid-Open No. 10-38800. According to this surface plasmon sensor, a transparent optical housing 12 is detachably put on a transparent substrate housing 11. The substrate housing 11 is provided with a light source unit 13 and a plurality of photoelectric detectors 14 arranged in a row. The optical housing 12 has a pentagonal or trapezoidal sectional configuration when viewed from the side thereof. A flat mirror 15 and a surface plasmon resonance layer 16 comprising an Au thin film, etc is provided on adjacent surfaces of the outer surfaces of the optical housing 12. Reference numeral 17 designates a spectrum filter.
Thus, according to the surface plasmon sensor, divergent light (polarized light) emitted from the light source unit 13 upward is reflected by the flat mirror 15 and falls onto the surface plasmon resonance layer 16; and the light reflected by the surface plasmon resonance layer 16 passes through the spectrum filter 17 and is received by the photoelectric detector 14. Here, since the divergent light falls on the surface plasmon resonance layer 16, each photoelectric detector 14 detects the intensity of the light inputted to the surface plasmon resonance layer 16 at different incident angles.
This surface plasmon sensor can be used as the biosensor as follows. On the condition that an antibody is fixed to the surface of the surface plasmon resonance layer 16, when an inspection sample solution containing an antigen that is specifically coupled to the antibody on the surface plasmon resonance layer 16 comes in contact with the antibody, the antigen is coupled to the antibody on the surface plasmon resonance layer 16. As a result, the refractive index at the interface of the surface plasmon resonance layer 16 varies and the intensity of the light received by the photoelectric detector 14 varies. Thus, when the variation of the light intensity is analyzed, it can be detected whether or not the inspection sample solution contains the antigen that is specifically coupled to the antibody on the surface plasmon resonance layer 16, or the density of the antigen can be measured.